Unit tests for ONOS are built using the JUnit framework, version 4.1112. Unit tests are used to verify correctness of implementations and are run as part of every full build of ONOS. The nightly SonarQube build runs all of the unit tests and produces coverage data that can be seen here.

Table of Contents

How to Write Good Tests

Unit tests should be as short, fast, and reliable as they can be. Every developer on the project will be running your tests, they should be easy to run and produce accurate results. Here are some key ways to write tests that are not brittle:

Avoid using sleep() whenever possible, since it often leads to brittle tests. If you find that you have to wait for an event or wait for some work to be done by another thread, prefer latches or thread notifications to sleeps.
Try to keep individual tests small, and only test one thing per test.
Use mocking when you need to include a complicated service to satisfy dependencies. ONOS uses the EasyMock framework, version 3.24.
Maven Bazel may choose to run multiple tests in the same Java virtual machine. If you use static variables in classes, be sure to reset them to known starting values before each test runs.
Do not use local resources like files and , ports, or IP Addresses in tests.

Basic Tests

...

A basic test for each one of your constructors and a check for the values returned by data access methods should always be included.

Code Block

language	java
title	Constructor and Accessor Check

    /**
     * Checks the construction of a FlowId object.
     */
    @Test
    public void testConstruction() {
        final long flowIdValue = 7777L;
        final FlowId flowId = FlowId.valueOf(flowIdValue);
        assertThat(flowId, is(notNullValue()));
        assertThat(flowId.value(), is(flowIdValue));
    }

Mocking

Mocking is a useful strategy for limiting the interaction between your code under test and other modules that are required to satisfy dependencies. There are several strategies that may be used for mocking, two that are used inside of ONOS are described here.

EasyMock Mocking Framework

EasyMock allows a test to create a mocked object directly from an interface, without having to define a class and mock every method defined by the API. The test writer can define only the methods that are required to execute the test. In this example, a mock is created for the HostService API which is passed in to the HostToHostIntentCompiler class.

Referencing Private Data

Sometimes when writing a test, you'll need to access data from a class that does not have a public API to access the data. In ONOS, we try to not add interfaces only used by test code. Instead, we have utility methods that use the Java reflection API to access this private data. In this example, the test verifies that the contents of the private intentsByLink member are correct using the TestUtils.getField() method to access the member.

Code Blockcode

language	java
title	EasyMock ExampleAccessing Private Data in a Test

import static org.easymockonlab.EasyMockjunit.*TestUtils;
 
    private@Test
 HostService mockHostService;
 
  public void privatetestLeaderEvents() staticthrows finalException String HOST_ONE_MAC = "00:00:00:00:00:01";
{
      private static final String HOST_TWO_MACObjectiveTracker tracker = "00:00:00:00:00:02";
 new ObjectiveTracker();

      private static final String HOST_ONE_VLAN = "-1";SetMultimap<LinkKey, IntentId> intentsByLink =
    private static final String HOST_TWO_VLAN = "-1";
    private  TestUtils.getField(tracker, "intentsByLink");
        assertThat(intentsByLink.size(), is(0));
    }

Mocking

Mocking is a useful strategy for limiting the interaction between your code under test and other modules that are required to satisfy dependencies. There are several strategies that may be used for mocking, two that are used inside of ONOS are described here.

EasyMock Mocking Framework

EasyMock allows a test to create a mocked object directly from an interface, without having to define a class and mock every method defined by the API. The test writer can define only the methods that are required to execute the test. In this example, a mock is created for the HostService API which is passed in to the HostToHostIntentCompiler class.

Code Block

language	java
title	EasyMock Example

import static org.easymock.EasyMock.*;
 
    private HostService mockHostServicestatic final String HOST_ONE = HOST_ONE_MAC + "/" + HOST_ONE_VLAN;
    private static final String HOST_TWO = HOST_TWO_MAC + "/" + HOST_TWO_VLAN;
    private HostId hostOneId = HostId.hostId(HOST_ONE);
    private HostId hostTwoId = HostId.hostId(HOST_TWO);
 
    @Test
    public void testHostToHostIntentCompiler() throws Exception {
        mockHostService = createMock(HostService.class);
        expect(mockHostService.getHost(eq(hostOneId))).andReturn(hostOne).anyTimes();
        expect(mockHostService.getHost(eq(hostTwoId))).andReturn(hostTwo).anyTimes();
        replay(mockHostService);
 
    private   static final HostToHostIntentCompiler compiler = new HostToHostIntentCompiler();
		compiler.hostService = mockHostService;

String HOST_ONE_MAC = "00:00:00:00:00:01";
    private static final String HOST_TWO_MAC = "00:00:00:00:00:02";
    private  static  final Intent intent = new HostToHostIntent(APPID, hid(oneIdString), hid(twoIdString),String HOST_ONE_VLAN = "-1";
    private static final String HOST_TWO_VLAN = "-1";
    private static final String HOST_ONE = HOST_ONE_MAC + "/"    + HOST_ONE_VLAN;
    private static final String HOST_TWO = HOST_TWO_MAC + "/" + HOST_TWO_VLAN;
    private HostId hostOneId     selector, treatment= HostId.hostId(HOST_ONE);
 
    private HostId hostTwoId  final List<Intent> result = compiler.compile(intent, null, null);
= HostId.hostId(HOST_TWO);
 
    @Test
    public void testHostToHostIntentCompiler() throws Exception {
        mockHostService assertThat(result, is(Matchers.notNullValue()))= EasyMock.createMock(HostService.class);
        assertThat(result, hasSize(2));
    }

Custom Mocks

Sometimes a test writer will want to implement their own complete mocked implementation of an API rather than use the mocking framework. This can be accomplished by creating a class that implements the API interface, and then implementing the methods to do whatever the test requires.

expect(mockHostService.getHost(eq(hostOneId))).andReturn(hostOne).anyTimes();
        expect(mockHostService.getHost(eq(hostTwoId))).andReturn(hostTwo).anyTimes();
        replay(mockHostService);
 
        final HostToHostIntentCompiler compiler = new HostToHostIntentCompiler();
		compiler.hostService = mockHostService;

        final Intent intent = new HostToHostIntent(APPID, hid(oneIdString), hid(twoIdString),
                                                   selector, treatment);
 
        final List<Intent> result = compiler.compile(intent, null, null);
        assertThat(result, is(Matchers.notNullValue()));
        assertThat(result, hasSize(2));
    }

Custom Mocks

Sometimes a test writer will want to implement their own complete mocked implementation of an API rather than use the mocking framework. This can be accomplished by creating a class that implements the API interface, and then implementing the methods to do whatever the test requires.

Code Block

language	java
title	Custom Mock Example

   private static class TestIntentCompilerError implements IntentCompiler<Intent> {
        @Override
        public List<Intent> compile(Intent intent, List<Intent> installable,
                                    Set<LinkResourceAllocations> resources) {
            throw new IntentCompilationException("Compilation always fails");
        }
    }
 
    /**
     * Tests for proper behavior of installation of an intent that triggers
     * a compilation error.
     */
    @Test
    public void errorIntentCompile()

Code Block

language	java
title	Custom Mock Example

   private static class TestIntentCompilerError implements IntentCompiler<Intent> {
        @Override
    final TestIntentCompilerError errorCompiler = new TestIntentCompilerError();
     public List<Intent> compile(Intent intent,final List<Intent>IntentManager installable,
intentManager = new IntentManager();
        final IntentExtensionService extensionService = intentManager;
        final IntentService intentService = intentManager;

         Set<LinkResourceAllocations> resources) {extensionService.registerCompiler(MyIntent.class, errorCompiler);
        MyIntent intent   throw= new IntentCompilationException("Compilation always fails"MyIntent();
        }
    }
 
    /**
     * Tests for proper behavior of installation of an intent that triggers
     * a compilation error.
     */
    @Test
    public void errorIntentCompile() { 
		// Invoke the error compiler
		intentService.submit(myIntent);
    }

Hamcrest

Hamcrest is a powerful framework for defining matchers for data values in tests. ONOS uses version 1.3 of Hamcrest. Contributors are encouraged to learn about and use the Hamcrest framework, particularly when working with arrays and collections. Hamcrest also gives you the ability to write your own matchers, which will make your tests easier to read and easier to extend by other developers.

Here is an example of a custom Hamcrest matcher, that matches a Criterion type in a TrafficSelector object:

Code Block

language	java
title	Hamcrest Matcher for Criterion Type

    /**
     * Hamcrest matcher finalto check TestIntentCompilerErrorthat errorCompilera =selector new TestIntentCompilerError();contains a
     * Criterion with finalthe IntentManagerspecified intentManagertype.
 = new IntentManager();
  */
    public static final IntentExtensionServiceclass extensionServiceCriterionExistsMatcher
 = intentManager;
        final IntentService intentServiceextends =TypeSafeMatcher<TrafficSelector> intentManager;{

        private extensionService.registerCompiler(MyIntent.class, errorCompiler)final Criterion.Type type;
        MyIntent/**
 intent = new MyIntent();
 
		// Invoke the error compiler
		intentService.submit(myIntent);
    }

Hamcrest

Hamcrest is a powerful framework for defining matchers for data values in tests. ONOS uses version 1.3 of Hamcrest. Contributors are encouraged to learn about and use the Hamcrest framework, particularly when working with arrays and collections. Hamcrest also gives you the ability to write your own matchers, which will make your tests easier to read and easier to extend by other developers.

Here is an example of a custom Hamcrest matcher, that matches a Criterion type in a TrafficSelector object:

Code Block

language	java
title	Hamcrest Matcher for Criterion Type

    /**     * Constructs a matcher for the given criterion type.
         *
         * @param typeValue criterion type to match
         */
        public CriterionExistsMatcher(Criterion.Type typeValue) {
            type = typeValue;
     *   Hamcrest}
 matcher to check that a selector contains a@Override
     *   Criterionpublic withboolean the specified type.
matchesSafely(TrafficSelector selector) {
      */
    public static final Set<Criterion> class CriterionExistsMatchercriteria = selector.criteria();
           extends TypeSafeMatcher<TrafficSelector> { return notNullValue().matches(criteria) &&
        private  final Criterion.Type type;
        /**
hasSize(1).matches(criteria) &&
           * Constructs a matcher for the given criterion type. notNullValue().matches(selector.getCriterion(type));
         *
}
        @Override
      * @param typeValuepublic criterionvoid type to matchdescribeTo(Description description) {
         */
    description.appendText("a criterion with type public CriterionExistsMatcher(Criterion.Type typeValue) {\" ").
            type = typeValue;
      appendText(type.toString()).
  }
        @Override
        public boolean matchesSafely(TrafficSelector selector) {appendText("\"");
            final Set<Criterion> criteria = selector.criteria();
   }
    }

    /**
     * Creates a criterion returntype notNullValue().matches(criteria) &&
   matcher.  Returns a matcher
     * for a criterion with the given type.
    hasSize(1).matches(criteria) &&
 *
     * @param type type of Criterion to match
     * @return  notNullValue().matches(selector.getCriterion(type));Matcher object
     */
   } @Factory
    public static Matcher<TrafficSelector>  @OverridehasCriterionWithType(Criterion.Type type) {
        publicreturn voidnew describeToCriterionExistsMatcher(Description description) {type);
    }
 
   /**
     description.appendText("a criterion with type \" ").
   * Tests the builder functions that add specific criteria.
     */
    @Test
    public void   appendText(type.toString()).testCriteriaCreation() {
        TrafficSelector  selector;

        selector = appendText("\"");DefaultTrafficSelector.builder()
        }
    }

    /**.matchInport(PortNumber.portNumber(11)).build();
     * Creates a criterion type matcher.  Returns a matcherassertThat(selector, hasCriterionWithType(Type.IN_PORT));
     * for a criterion with the given type.
     *
     * @param type type of Criterion to match
     * @return Matcher object
     */
    @Factory
    public static Matcher<TrafficSelector> hasCriterionWithType(Criterion.Type type) {
        return new CriterionExistsMatcher(type);
    }
 
   /**}

Add library for Unit Test

If you are using a library for Unit Test other than the above, please add the library to the build path. You can modify the lib/deps.json file where we keep track of external libraries:

Code Block

language	bash
title	Modify the lib/deps.json file

vi lib/deps.json

Code Block

title	lib/deps.json

{
 "libraries": {
・・・
,
    "TEST": [
      "[new library name]",
     * Tests"junit",
 the builder functions that add specific criteria. "easymock",
     */
    @Test "hamcrest-all",
    public void testCriteriaCreation() { "hamcrest-optional",
      "guava-testlib",
  TrafficSelector selector;

   "//utils/junit:onlab-junit"
     selector = DefaultTrafficSelector.builder()],
・・・
 },


 "artifacts": {
・・・
    "jsch":"mvn:com.jcraft:jsch:0.1.53",
    "[new library name]":"mvn:[new library     .matchInport(PortNumber.portNumber(11)).build();path]:[new library version]",
    "junit":"mvn:junit:junit:4.12",
    assertThat(selector, hasCriterionWithType(Type.IN_PORT));
    }

...

"junit-dep":"mvn:junit:junit:4.10",
・・・
 }
}

...and then run onos-lib-gen tool to re-generate the Bazel workspace file.

Code Block

language	bash
title	Re-generate Bazel workspace

tools/build/onos-lib-gen

...

Home : Contributing to the ONOS Codebase

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New Version Current

Key

How to Write Good Tests

Basic Tests

Mocking

EasyMock Mocking Framework

Referencing Private Data

Mocking

EasyMock Mocking Framework

Custom Mocks

Custom Mocks

Hamcrest

Hamcrest

Add library for Unit Test

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Page History

Versions Compared

Old Version 24

New Version Current

Key

How to Write Good Tests

Basic Tests

Mocking

EasyMock Mocking Framework

Referencing Private Data

Mocking

EasyMock Mocking Framework

Custom Mocks

Custom Mocks

Hamcrest

Hamcrest

Add library for Unit Test